Introduction into the environment of elements (such as arsenic, cadmium, lead, and mercury) which have a deleterious effect on living organisms when found naturally in only minor amounts (concentrations less than 1.0 milligram per liter) in water or sediment.

Trace elements are inorganic chemicals occurring in small amounts in nature. This web site of the National Water Quality Assessment links to U.S. data, publications, news, and other sites on trace metals, metalloids and radionuclides in water.

Explains the natural and human-affected factors that determine the concentration of contaminants in groundwater, especially where the concentration is different at the surface than at depth, and where pumping varies with time.

Arsenic is a naturally occurring element in rocks, soils, and the waters in contact with them. It is found in ground water as the result of minerals dissolving from weathered rocks and soils. This site links to data, maps, and more.

Information on arsenic in United States ground water largely as a result of minerals dissolving from weathered rocks and soils. Includes links to publications, data, maps, and links to other sites with information on arsenic.

Maps and text (Word or PDF format) and database (Excel or HTML format) for bedrock, forest floor, and mineral soil sampling in Voyageurs National Park, Minnesota to establish the background and baseline geochemistry and terrestrial mercury sources.

Reviews how coal fires occur, how they can be detected by airborne and remote surveys, and, most importantly, the impact coal-fire emissions may have on the environment and human health, especially mercury, carbon dioxide, carbon monoxide, and methane.

Collection of six short papers related to the mercury geochemical society, the study of mercury in coal, concentrations in sediment, soil, water, and fish collected near mercury and gold mines, and volanic emissions of mercury.

Trace elements were present at high concentrations in 32% of the primary aquifers here, and at moderate concentrations in 17%. Of particular interest are aluminum, arsenic, vanadium, boron, fluoride, chromium, lead, and molybdenum.

Five trace elements with human-health concerns were detected at high concentrations: arsenic, boron, molybdenum, strontium, and vanadium. Chromium and fluoride were detected at moderate concentrations.

Uranium, arsenic, and nitrate were the inorganic constituents that were most frequently detected at high concentrations, mostly in shallower wells. High and moderate concentrations of arsenic were detected in deeper wells.

Arsenic and boron were the trace elements that most frequently occurred at high concentrations. Fumigants (pesticides) were detected at high concentrations in 3% of the primary aquifers. Herbicides and insecticides were detected at low concentrations.

Recent study indicating inorganic constituents as the primary items of concern in this area. Chemical and mineralogical compositions of the aquifer rocks probably explain variation among localities here.

Coordinated studies of the effect of historical mining for mercury, origin and composition of metals in groundwaters and surface waters, history of volcanic and intrusive activity, and the complex geological history of this area.